OHM METER
This Arduino code reads the analog input from pin A0, which is connected to a resistor in a voltage divider configuration. It then calculates the resistance based on the voltage read from the analog pin. The calculated resistance value is displayed both on the Serial Monitor and an LCD screen using the I2C protocol.
Here's a simple and practical project idea for Arduino enthusiasts. If deciphering the color bands on resistors feels challenging, this project is tailor-made for you. Rather than grappling with deciphering colors each time you need to determine a resistor's resistance, why not construct an Ohm meter? With this tool, you can effortlessly measure the resistance of all your resistors. Additionally, if you devise a systematic way to label and arrange them, you'll eliminate the need to waste time distinguishing between those minuscule grey and purple bands ever again.
In the setup depicted in the picture, you'll need an Arduino board along with two resistors. One resistor, seen vertically in the image, should have a known resistance value, such as 10k ohms. The other resistor, which is positioned horizontally in the picture, is the one whose resistance we want to determine. This resistor is referred to as the unknown resistor. By configuring a voltage divider with these two resistors, we can measure the voltage across them using the Arduino. Then, through the application of Ohm's Law, our program will compute the resistance of the unknown resistor based on the measured voltage.
Arduino code below with detailed comments explaining each part to someone who's new to programming
/* Author: Douglas Fessler Date: 2024-03-26 This Arduino code reads the analog input from pin A0, which is connected to a resistor in a voltage divider configuration. It then calculates the resistance based on the voltage read from the analog pin. The calculated resistance value is displayed both on the Serial Monitor and an LCD screen using the I2C protocol.*/
#include <Wire.h>#include <LiquidCrystal_I2C.h>
// Set the LCD address to 0x27 for a 16 chars and 2 line displayLiquidCrystal_I2C lcd(0x27, 16, 2); // Change 0x27 to your LCD's I2C address if different
void setup() { Serial.begin(9600); lcd.init(); lcd.backlight(); lcd.setCursor(0, 0); lcd.print("RESISTANCE");}
void loop() { int sensorValue = analogRead(A0); // Read analog input from pin A0 float voltage = sensorValue * (5.0 / 1023.0); // Convert analog reading to voltage float resistance = (5.0 * 10000.0) / voltage - 10000.0; // Calculate resistance value using voltage divider formula // Print resistance to Serial Monitor Serial.print("Resistance: "); Serial.print(resistance); Serial.println(" Ohms"); // Print resistance to LCD lcd.setCursor(0, 1); lcd.print(" "); // Clear previous reading lcd.setCursor(0, 1); lcd.print(resistance); lcd.print(" Ohms"); delay(3000); // Delay for readability, adjust as needed}
Now, let's go through each part:
Initialization:
The necessary libraries (Wire.h and LiquidCrystal_I2C.h) are included.
An object lcd of class LiquidCrystal_I2C is created, representing the LCD screen. The I2C address of the LCD is set to 0x27, and it's configured as a 16x2 display. You may need to adjust the address if your LCD has a different address.
Setup Function (void setup()):
Serial communication is started at a baud rate of 9600.
The LCD is initialized.
The backlight of the LCD is turned on.
The cursor of the LCD is positioned at the beginning of the first line, and the text "RESISTANCE" is printed on it.
Loop Function (void loop()):
An analog reading is taken from pin A0 using analogRead(). This pin is connected to a voltage divider circuit containing a resistor whose resistance we want to measure.
The analog reading is converted to voltage using the formula (analog reading * 5.0) / 1023.0.
The resistance of the resistor in the voltage divider circuit is calculated using the formula (5.0 * 10000.0) / voltage - 10000.0. This calculation assumes a known reference resistor of 10kΩ.
The calculated resistance value is printed to the Serial Monitor with the message "Resistance: [value] Ohms".
The LCD is updated:
The second line is cleared.
The cursor is moved to the beginning of the second line.
The calculated resistance value is printed on the LCD.
"Ohms" is also printed next to the resistance value.
There's a delay of 3000 milliseconds (3 seconds) using delay() for readability before the next iteration of the loop.
Continuation:
The loop repeats continuously, continuously updating the resistance value read from the voltage divider circuit on both the Serial Monitor and the LCD screen.
Overall, the code continuously reads the analog value from a voltage divider circuit, calculates the resistance based on this value, and displays the resistance value on both the Serial Monitor and an LCD screen.
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